With that, can I assume that the cause is the network traffic? Since all LANs uses 1 physical network card?
Is there anything we can adjust in Oracle? is there a Timeout settings that can be configured? Or we need to adjust the hardware already?

What will be the effect if we increase the misscount parameter? Will that greatly impact the performance?

==
Increasing misscount will prolong the time to take corrective action in the event of network failure or other anomalies effecting the availability of a node in the cluster. This directly effects cluster availability.
==

By here..
<<https://support.oracle.com/CSP/main/article?cmd=show&type=NOT&id=294430.1>>

you need to add this line in Red Hat Enterprise Linux 4.vmx so that disk will not hang.
reslck.timeout="1200"

May be your disks I/O is more and because of that node was rebooted, try above command.

Thanks for this, can you explain it further? Are you saying that network might not be the problem, and it might be the disk i/o?
We have already added network cable, so the setup now is each VM are assigned to 1 vSwitch which has 1 physical network cable connected, but we still encountered the same error.
When we added the network cable, we have successfully imported 2 user schemas and data. But now, we still experience the same issue.